Although similarity is important, it is not the only factor that creates a group. Groups have more entitativity when the group members have frequent interaction and communication with each other (Johnson & Johnson, 2012). Although communication can occur in groups that meet together in a single place, it can also occur among individuals who are at great distances from each other. The members of a research team who communicate regularly via Skype, for instance, might have frequent interactions and feel as if they are a group even though they never or rarely meet in person.
Interaction is particularly important when it is accompanied by interdependence—the extent to which the group members are mutually dependent upon each other to reach a goal. In some cases, and particularly in working groups, interdependence involves the need to work together to successfully accomplish a task. Individuals playing baseball are dependent upon each other to be able to play the game and also to play well. Each individual must do his or her job in order for the group to function. We are also interdependent when we work together to write a research article or create a class project. When group members are interdependent, they report liking each other more, tend to cooperate and communicate with each other to a greater extent, and may be more productive (Deutsch, 1949).
Still another aspect of working groups whose members spend some time working together and that makes them seem “groupy” is that they develop group structure—the stable norms and roles that define the appropriate behaviors for the group as a whole and for each of the members. The relevant social norms for groups include customs, traditions, standards, and rules, as well as the general values of the group. Particularly important here are injunctive norms, which specify how group members are expected to behave. Some of these are prescriptive norms, which tell the group members what to do, whereas some are proscriptive norms, which tell them what not to do. In general, the more clearly defined and the widely agreed upon the norms in a group are, the more entitativity that the group members will feel.
Effective groups also develop and assign social roles (the expected behaviors) to group members. For instance, some groups may be structured such that they have a president, a secretary, and many different working committees. Different roles often come with different levels of status, or perceived power, and these hierarchies. In general, groups are more effective when the roles assigned to each member are clearly defined and appropriate to those individuals’ skills and goals. Also, if members have more than one role, for example, player and coach, it is important that these roles are compatible rather than contradictory. High-performing groups are thus able to avoid placing members under role stress. This occurs when individuals experience incompatible demands and expectations within or between the roles that they occupy, which often negatively impacts their ability to be successful in those roles (Forsyth, 2010).